Three fiber line switched ring

A 3 fiber line switched ring (3FLSR) provides protection for (optical) transmission networking wherein N nodes are connected via 3 lines (or optical fibers) in a ring topology. Two of the three fibers form a main transmission line and may transmit in one direction in the ring whereas the third might transmit in the opposite direction. This architecture of the 3FLSR provides a dual protection scheme, including a bi-directional line switching coupled with a unidirectional line switching. Traffic is categorized based on the level of protection available for the particular traffic type. The first two transmitting fibers form a bi-directional ring, carrying primary and secondary traffic which can survive 2 and 1 failures on the ring respectively. The third fiber may form a unidirectional ring, carrying additional traffic that can be pre-empted in case of multiple failures in the bi-directional ring. The 3FLSR enables reconfiguration of existing 2/4 fiber rings and conforms to applicable standards.